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I am in the process of fixing my K100 and I have noticed antifreeze gell globs in the coolant passages and the waterpump. I have read the BMW bulletin that is attached to this post and was wondering what is the best product to use to flush this gell out before I put in the new BMW antifreeze?

I found that attachment very interesting, if only for BMW to justify their antifreeze product!

I do agree that reducing the antifreeze mix to 40/60 water improves cooling if you don't need the lower freezing temperature protection.

As for the Gel, the article seems to suggest that one cause of Gel build up can be corrosion which is a bit scary. It also mentions calcium in water so one rule there could be to make up the coolant mix with de-ionised water.

I'm no chemist, but I have a few ideas. I'm wondering if this Gel forms more easily with 50/50 mixes - the higher the concentration the more easily it stays insoluble and if it is left in there for longer than say a couple of years. I note what they say about changes in the chemical mix of non-BMW antifreezes, but are they saying that 100's of 1000's of cars are all running around with gelled coolant, blockages and overheating?

I think the reason K motors get so hot, is they don't design their cooling systems well enough. If the sustained heat cycling and hot running can cause coolant gelling, then I blame the design, not their fix to bring out a new antifreeze or criticism of other formulae widely used in vehicles that don't suffer extreme heat changes in their cooling systems!

What to do? I'm no chemist but I'd suggest filling the system with clean water, run the bike to fans on on the stand for 15 minutes or so whilst burping the hoses. Switch off and let the bike cool, drain and refill again and repeat. Do this 3 times, then refill with a new coolant mix using de-ionised water. I'm suggesting this because the Gel, may be more soluble in clean hot water, than in a coolant mix. You could always fish some out and shake it up with hot water to see if it dissolves. If it doesn't then we are looking for an alternative chemical solvent. You could test samples with petrol, alcohol, brake cleaner etc. Whilst you won't be filling up your system with these, you could use solvents to flush through each rad. off the bike, then follow up with plenty of water.

The most important place to get 'Gel free' are the radiators as they have the smallest holes! If you wanted to go the full hog you could make up an adaptor to your garden hose and push clean water through.

You raise an interesting point relevant to all the K's, because they all get too hot, except my KRS that has been running with 4 cooling fans. for a few years now.

I've heard of gelling occurring when different types of antifreeze are mixed. IIRC, it was mixing certain long life antifreezes (OAT coolants). Pretty much anecdotal, but it seems like even mechanics who think it isn't a big deal, don't suggest mixing different types. And when I say "type" I'm talking chemical makeup, not brand or color.

I am in the process of fixing my K100 and I have noticed antifreeze gell globs in the coolant passages and the waterpump. I have read the BMW bulletin that is attached to this post and was wondering what is the best product to use to flush this gell out before I put in the new BMW antifreeze?

cheers,
Ron

Don't know about the best procedure but I've used Robert Fleisher's (Snowbum) site for advice on how to fix my Airhead and do some procedures on my K75. He has a recommended procedure for flushing the radiator and mixing a 40/60 ratio of coolant.

I am in the process of fixing my K100 and I have noticed antifreeze gell globs in the coolant passages and the waterpump. I have read the BMW bulletin that is attached to this post and was wondering what is the best product to use to flush this gell out before I put in the new BMW antifreeze?

cheers,
Ron

You might want to try Honda Type 2 Automotive antifreeze, I have used it for years in two K100's I have and my cooling systems both look pristine inside. It comes 50/50 premix. The one K100 I had that used BMW coolant has a buildup of deposits in the system.